Sky Sports: "With transfers of young players meaning many footballers spend different phases of their development at different clubs, gauging how many players a club has developed is a complex matter. So for this study we established three key rules. Players are only considered if…
- They joined their club before their 18th birthday
- They played for their club's U18 side or equivalent
- They had not played a senior match for another professional team before joining their current club"
